Emission reduction from mobile sources by on-board carbon dioxide conversion to fuel

ABSTRACT

An apparatus and process for reducing vehicle emissions by converting exhaust gases to hydrocarbon fuel. The apparatus and process supplement conventional emission control techniques to further reduce vehicle emissions of harmful substances. The apparatus includes a heat exchanger to extract thermal energy from exhaust gases of a combustion engine that powers propulsion of a vehicle, a membrane separator to separate water and carbon dioxide from the exhaust gases, and a catalytic reactor comprising a nano catalyst. The catalytic reactor receives the water and the carbon dioxide from the membrane separator, contains a reaction of the water and the carbon dioxide that produces hydrocarbon fuel and is facilitated by the nano catalyst, and uses the thermal energy from the heat exchanger to stimulate the reaction. The catalytic reactor is contained within a body of the heat exchanger to facilitate the transfer of thermal energy.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of U.S.Provisional Patent Application No. 61/550,699, attorney docket number004159.007037, filed on Oct. 24, 2011 the disclosure of which isincorporated by reference herein in its entirety.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a process for reducing vehicleemissions by converting carbon dioxide to hydrocarbon fuel. Morespecifically, embodiments of the present invention utilize an on-boardheat exchanger and catalytic converter to convert vehicle exhaust intohydrocarbon fuel for the vehicle's combustion engine.

BACKGROUND OF THE INVENTION

The automobile industry has recognized for decades that vehicleemissions are harmful to the public health and the environment. It isalso well-known that conventional methods of reducing vehicle emissionsare inefficient. Typically, vehicle emissions may be reduced byincreasing engine efficiency and/or cleansing the exhaust aftercombustion. For example, vehicle exhaust may be cleansed using secondaryair injection, exhaust gas recirculation, and/or catalytic conversion.

Typically, a catalytic converter includes metallic catalyst(s) (e.g.,platinum, palladium, rhodium) for converting toxic emissions intonon-toxic substances. The toxic emissions converted may include carbonmonoxide, nitrogen oxides, and unburned hydrocarbons. For example, thecarbon monoxide may be oxidized and converted to carbon dioxide, wherethe catalyst stimulates the oxidation.

The use of a catalytic converter fails to resolve all the challengesrelated to reducing vehicle emissions. For example, catalytic convertersfail to reduce the amount of hydrocarbon fuel being combusted. Further,catalytic converters produce carbon dioxide, which is a greenhouse gasthat contributes to global warming.

Therefore, it would be desirable to have an improved process forreducing vehicle emissions. Preferably, it would be desirable to have aprocess that converts emissions into usable fuel. Further, it would bedesirable to have a process that also reduces the amount of carbondioxide being emitted.

SUMMARY OF THE INVENTION

In one embodiment, the apparatus for emission reduction from mobilesources includes a heat exchanger to extract thermal energy from exhaustgases of a combustion engine, the combustion engine powering propulsionof a vehicle; a membrane separator to separate water and carbon dioxidefrom the exhaust gases; and a catalytic reactor having a nano catalyst,the catalytic reactor to contain a reaction of the water and the carbondioxide that produces hydrocarbon fuel, the reaction being facilitatedby the nano catalyst. In one embodiment, the catalytic reactor receivesthe water and the carbon dioxide from the membrane separator and usesthe thermal energy from the heat exchanger to stimulate the reaction ofthe water and the carbon dioxide.

In one embodiment, the nano catalyst is a multimetallic nano catalystthat includes at least one of ruthenium, manganese, and nickel. Inanother embodiment, the nano catalyst is about 2 to 3 percent ruthenium,about 20 to 30 percent nickel, and about 15 to 20 percent manganese. Inyet another embodiment, the nano catalyst is about 2 percent ruthenium;about 20 percent nickel, and about 15 percent manganese.

In one embodiment, the membrane separator includes a selective membranelayer that is a silica-based membrane layer, a carbon-based membranelayer, or a zeolite membrane layer and a support layer that is a ceramicsupport, a metallic support, or an alumina support.

In one embodiment, the catalytic reactor is encompassed by the heatexchanger such that the thermal energy is directed to a portion of thecatalytic reactor holding the nano catalyst. In one embodiment, thecatalytic reactor includes multiple tubes for holding the nano catalyst,the multiple tubes providing increased surface area for receiving thethermal energy from the heat exchanger.

In one embodiment, the hydrocarbon fuel includes ethanol and propyne.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, claims, and accompanying drawings. It is to be noted,however, that the drawings illustrate only several embodiments of theinvention and are therefore not to be considered limiting of theinvention's scope as it can admit to other equally effectiveembodiments.

FIG. 1 shows an apparatus in accordance with one or more embodiments ofthe present invention.

FIG. 2 shows a process flow in accordance with one or more embodimentsof the present invention.

FIG. 3 shows an example apparatus in accordance with one or moreembodiments of the present invention.

FIG. 4 shows a heat exchanger and catalytic reactor in accordance withone or more embodiments of the present tion.

FIG. 5 shows a heat exchanger in accordance with one or more embodimentsof the present invention.

DETAILED DESCRIPTION

While the invention will be described in connection with severalembodiments, it will be understood that it is not intended to limit theinvention to those embodiments. On the contrary, it is intended to coverall the alternatives, modifications and equivalence as may be includedwithin the spirit and scope of the invention defined by the appendedclaims.

In one embodiment, an apparatus for emission reduction of vehiclesincludes a heat exchanger for extracting thermal energy from exhaust gasof a combustion vehicle, the combustion engine powering propulsion of avehicle; a membrane separator for separating water and carbon dioxidefrom the exhaust gas; and a catalytic reactor comprising a nano catalystfor containing a reaction of the water and carbon dioxide that produceshydrocarbon fuel. Further, the thermal energy extracted by the heatexchanger stimulates the reaction of the water and the carbon dioxide.

As shown in FIG. 1, the apparatus 100 comprises an integrated heatexchanger 102A and catalytic reactor 102B, a catalytic converter 104, acoil-type heat exchanger 106, a membrane separator 108, and an exhaust110. In one embodiment, the apparatus 100 is incorporated into theexhaust system of a vehicle (e.g., installed on the undercarriage of thevehicle) as discussed below with respect to FIG. 3.

In one embodiment, the heat exchanger 102A and catalytic reactor 102Bare integrated so that thermal energy extracted from exhaust gases inthe heat exchanger 102A can be used to stimulate a reaction in thecatalytic reactor 102B. The heat exchanger 102A receives the exhaustgases from a combustion engine. Thermal energy is extracted from theexhaust gases as they pass through the heat exchanger 102A therebycooling down the exhaust gases before the exhaust gases enter thecatalytic converter 104. The heat exchanger 102A allows for (1) wasteheat to be recovered from the engine and used by the catalytic reactor102B and (2) exhaust gases to be cooled before entering the othercomponents of the apparatus 100. For example, the membrane separator 108can include a membrane that operates at relatively high pressure andtemperatures lower than the temperature of the exhaust gas exiting thecombustion engine.

In some embodiments, the catalytic reactor 102B includes a catalyticsystem, a photo-catalytic system, an electro-catalytic system, orsuitable combination thereof. Further, the catalytic reactor 102B caninclude a fixed, fluidized bed and a catalytic membrane. The catalystcan be a supported nanostructure catalyst that includes alumina, silica,and clay as support and active monometallic, hi-metallic andtri-metallic materials as active ingredients as discussed below.

In one embodiment, the catalytic reactor 10213 contains a reaction toconvert CO₂ and H₂O to hydrocarbon fuel. For example, the reaction canbe a general reaction to produce alcohols such as: nCO₂+(n+1)H₂O→C_(n)H_(2n+1) OH+(3n/2) O₂, where n=1, 2, 3, 4, 5, 6, etc, (e.g., when n=1then the product is CH₃OH (methanol), when n=2 then the product isC₂H₅OH (ethanol), etc.). In another example, the reaction can betargeted for alkane production such as: 2nHO+nCO₂→C_(n)H_(2n+2)+2nO₂,where n=3, 4, 5, 6, etc. In yet another example, the reaction canproduce methane (CH₄) or mixed products with the release of oxygen asshown in the following reactions:

-   -   A catalyst stimulated reaction producing ethanol, propyne, and        oxygen at 673 K and atmospheric        pressure—5CO₂+5H₂O→C₂H₅OH+H₃C—C≡CH+7 O₂    -   A catalyst stimulated reaction producing methanol, ethanol,        oxygen, and propyrte—6CO₂+7H₂O→CH₃OH+C₂H₅OH+17/2 O₂+H₃C—C≡CH

In this example, the catalyst and reaction temperature can be tailoredto maximize the production of certain products (e.g., ethanol). Further,the nano catalyst used by the catalytic reactor 102B can be a metallicnano catalyst including ruthenium, manganese, and/or nickel.Specifically, the metallic nano catalyst can be about 2 to 3 percentruthenium, about 20 to 30 percent nickel, and about 15 to 20 percentmanganese (e.g., 2 percent Ruthenium, 20 percent Nickel, and 15 percentManganese). The reaction can be stimulated by the catalyst when H₂O(steam) and CO₂ decompose over the nano catalyst surface to produceOxygen and hydrogen. At this stage, the hydrogen and oxygen can reactwith the carbon to produce the hydrocarbon fuel. In some cases, nascentoxygen resulting from the reaction can result in the generation ofadditional energy, which reduces the requirement for external thermalenergy.

An example nano catalyst is described in Hussain S. T., et al., NanoCatalyst for CO ₂ Conversion to Hydrocarbons, Journal of Nano Systems &Technology, Oct. 31, 2009. In this article, the example nano catalyst isprepared as follows:

-   -   A solution of ruthenium trichloride (0.103 g), manganese nitrate        tetrahydrate (2.285 g) and nickel nitrate hexahydrate (2.47 g)        (analar grade) is prepared in deionized H₂O and acidified with        dilute hydrochloric acid to prevent the precipitation of        hydroxide.    -   A portion of the slurry (10 cm3) is then added to a titanium        dioxide catalyst support (3.95 g), (350 m²g⁻¹) in an evaporation        basin, where the mixture is magnetically stirred for 20 minutes        and dried at 395 K overnight.    -   The prepared catalyst sample is then calcined in air for 6 hours        at 600° C.

Based on a typical driving cycle (e.g. the USO6 drive cycle), exhaustgases can be emitted from 6.5 grains/sec to 200 grams/sec depending thespeed of the vehicle. In this case, the maximum speed in the drivingcycle is around 80 mph, which can be used to calculate a quantity ofcatalyst for commercial purposes. In laboratory tests, the amount ofcatalyst used was 0.5 grams, where the corresponding space velocity ofthe exhaust through the reactor was 6000-7200 hr⁻¹. Comparatively, theexhaust mass flow rate through a vehicle can vary from 6.5 g/s to 200g/s. In some embodiments, based on the laboratory quantity and thetypical driving cycle, the total amount of catalyst used in thecatalytic reactor 102B is about 120 grams. In this case, the level ofconversion of in the reactor is dependent on the exhaust mass flow rate(i.e., the conversion rate in the reactor increases as the exhaust massflow rate decreases).

In one embodiment, the catalytic converter 104 cleanses toxic substancesfrom the vehicle exhaust. Specifically, the catalytic converter 104 caninclude metallic catalysts for (1) oxidizing carbon monoxide to generateCO₂ and (2) oxidizing unburned hydrocarbons to generate H₂O and CO₂. Thereactions in the catalytic converter 104 increase the temperature of theexhaust gases before they are passed to a coil type heat exchanger 106.

In one embodiment, the coil type heat exchanger 106 reduces thetemperature of the exhaust gas before it is provided to the membraneseparator 108. The coil type heat exchanger 106 can transfer thermalenergy from the exhaust gas to reactants traveling towards the catalyticreactor 102B.

In one embodiment, the membrane separator 108 separates CO₂ and H₂O fromthe other gases of the exhaust gases received from the coil type heatexchanger 106. The membrane separator 108 can include a variety ofmembranes, where the CO₂ and H₂O is separated as permeate or retenatedepending on the operating conditions (e.g., temperature). The separatedCO₂ and H₂O are passed to the catalytic reactor 102B, and the othergases as passed to the exhaust 110. The exhaust 110 can then emit theother gases from the vehicle.

Turning to FIG. 2, an example process flow for converting exhaust gasesto hydrocarbon fuel is shown. In 202, the exhaust gases leaving thevehicle engine enter a double-pipe heat exchanger 102A at a temperatureof about 850° C. (i.e., the exhaust gases contain energy in the form ofheat generated from combustion in the vehicle engine). The double-pipeheat exchanger 102A extracts thermal energy from the exhaust gasesbefore emitting the exhaust gas in 203. The exhaust gases leave thedouble-pipe heat exchanger 102A at a temperature of about 350-500° C.before entering the catalytic converter 104. In the catalytic converter104 reactions occur to convert unburned gaseous components into N₂, CO₂,H₂O, etc. In 204, the converted gases leave the catalytic converter 106at a temperature of about 500-600° C.

The converted gases then pass through a coil type heat exchanger 106 totransfer further heat to reactants moving towards the catalytic reactor102B. In 206, the converted gases enter the membrane separator 108 atabout 200-300° C. In the membrane separator 108, CO₂ and H₂O areseparated from the converted gases. In 210, the separated CO₂ and H₂Opass through the coil-type heat exchanger 106 to raise the temperatureof the CO₂ and H₂O to about 500° C. in 110, the remaining gases leavethe membrane separator 108 and are emitted from the vehicle as exhaust.In 212, the heated CO₂ and H₂O are passed to the catalytic reactor 102B.In the catalytic reactor 102B, a nano catalyst stimulates a reactionthat converts the CO₂ and H₂O into hydrocarbon fuel. In 214, thehydrocarbon fuel is recycled into the car engine 216 (e.g., thehydrocarbon fuel can be passed to a fuel line, a carburetor, or a fueltank) thereby reducing CO₂ emissions from the vehicle.

The process flow arrangement of FIG. 2 cools the exhaust gases so thatCO₂ and H₂O can be separated from the exhaust gases at low temperaturesin the membrane separator 108. At the same time, the temperature of theseparated CO₂ and H₂O moving towards the catalytic reactor 102B israised by heat transfer from both the double-pipe heat exchanger 102Aand coil-type heat exchanger 106. In some embodiments, the process flowarrangement utilizes the waste heat of the exhaust gases so that thereaction can be performed without external energy. The process flowarrangement can be installed on the undercarriage of the vehicle alongthe exhaust pipe as discussed below with respect to FIG. 3.

Turning to FIG. 3, an example apparatus installed on a vehicleundercarriage 302 is shown. An exhaust head pipe 306 of the vehiclereceives exhaust gases from a combustion engine (not shown). Theintegrated heat exchanger 102A and catalytic reactor 102B is attached tothe exhaust head pipe 306. In this example, the exhaust head pipe 306and integrated heat exchanger 102A and catalytic reactor 102B arepositioned under an engine section 304 of the vehicle (i.e., positionedunder the combustion engine of the vehicle). Exhaust gases from theexhaust head pipe 306 are conveyed through the heat exchanger 102A tothe catalytic converter 104.

Adjacent the engine section 304 is a heat shield 306 for protecting thevehicle from the heat of the exhaust gas as it passes through theexample apparatus. In this example, the heat shield 306 encompasses thecatalytic converter 104, the coil-type heat exchanger 106, the membraneseparator 108, and the exhaust 110, each of which may be substantiallysimilar to the respective components described above with respect toFIGS. 1 and 2. As shown in FIG. 3, permeate 210 CO₂ and H₂O) from themembrane separator 108 is conveyed to the coil-type heat exchanger 106,which transfers thermal energy from the exhaust gas to the permeate 210.The heated reactants 212 are then conveyed past the catalytic converter104 to the catalytic reactor 102B. Further thermal energy can betransferred to the heated reactants 212 from the catalytic converter 104and the heat exchanger 102A as the heated reactants flow towards and inthe catalytic reactor 102B. The catalytic reactor 102B converts theheated reactants 212 to hydrocarbon fuel 214, which is then used asrecycled fuel 216 for the vehicle.

Turning to FIG. 4, an example integrated heat exchanger and catalyticreactor 102A, 102B is shown. As discussed above, the integrated heatexchanger and catalytic reactor 102A, 102B can be installed between thecombustion engine and the catalytic converter on a vehicleundercarriage. The exhaust gases 202 typically leave the engine ataround 800 to 900° C. and are quickly cooled to about 500 to 600° C.before leaving an outer pipe 402 of the integrated heat exchanger andcatalytic reactor 102A, 102B. The integrated heat exchanger andcatalytic reactor 102A, 102B is positioned to recover waste heat fromthe exhaust gases 202 and to supplement the heat requirements ofendothermic reactions taking place in an inner pipe 404 of theintegrated heat exchanger and catalytic reactor 102A, 102B.

In this example, the integrated heat exchanger and catalytic reactor102A, 102B is a standard double-pipe heat exchanger in which the innerpipe 404 holds the catalyst 406 for reaction and the outer pipe 402provide the passage for the exhaust gas. In another example, theintegrated heat exchanger and catalytic reactor 102A, 102B can be ashell and tube type heat exchanger including an inside shell havingmultiple tubes holding the catalyst 406, where the multiple tubes can beattached to tube-sheets at both ends of the double-pipe heat exchanger.The multiple tubes provide a larger surface area for the heat transfer.In either example, the outer pipe 402 can be properly insulated toconserve heat and facilitate the heat transfer.

Turning to FIG. 5, an example membrane separator 108 is shown. Themembrane separator 108 includes a membrane 502 for separating permeate210 (CO₂ and H₂O) from exhaust gases received from the catalyticconverter 206. In some embodiments, the membrane 502 can have a hollowfiber configuration. In this case, the membrane 502 includes a selectivemembrane layer (not shown) that is coated on stable supports (e.g.,ceramic hollow fibers, etc.). In other embodiments, the membrane 502 canhave a tubular configuration. In this case, the selective membrane layeris coated on a porous tubular support (e.g., porous alumina tubes,ceramic tubes, porous metallic tubes, etc.). Optionally, sweep gas (notshown) can be injected into the membrane separator 108 to facilitate thecollection of the permeate 210. Table I below shows example membranesthat can be used in the membrane separator 108.

TABLE I Example Membranes for Membrane Separator 108 Selective membraneExample # layer material Support layer 1 Silica Ceramic support withalumina/zirconia interlayer 2 Silica Porous metallic support withzirconias or alumina interlayer 3 Cobalt embedded silica Porousmetallic/ceramic support 4 Carbon molecular sieve (CMS) Alumina support5 Y-type zeolites Alumina support 6 Carbon based (prepared by Aluminasupport carbonization of polyimides or similar polymers) 7 Faujasite(FAU)-type zeolite

The present invention is illustrated by the following example, which ispresented for illustrative purposes only and is not intended as limitingthe scope of the invention which is defined by the appended claims.

Example Thermal Study

A study was performed to characterize (1) the heat released from theexhaust gases, (2) the temperature of the exhaust gases, and (3) theemission composition. In addition, thermodynamic calculations for anexhaust system (e.g., apparatus 100 of FIG. 1) were performed. Specifictasks performed in the study include:

-   -   Estimating exhaust gases temperature.    -   Determining an availability of energy from exhaust engine gases        for operating the catalytic reactor at 800 to 850° C.    -   Determining a composition of exhaust emissions.

Thermodynamic simulations of engine cycles, delivered power (i.e.;indicated mean effective pressure (IMEP)), engine efficiencies, fuelconsumption, estimated exhaust temperatures and emissions were conductedusing a gas-dynamics engine system simulation platform. Specifically,calculations were performed using the gas-dynamics engine systemsimulation platform with input data based on a modern single cylinderspark ignition engine as used in laboratory testing, where the ignitionengine had inlet and exhaust geometry and Port Fuel Injection (PFI). Themodel was fully validated for different fuels and combustion conditionsagainst available experimental data. Further, the conditions and gasdynamics of the engine inlet and exhaust geometry were based on thelaboratory engine, and the heat transfer in the laboratory engine wasbased on typical default values. Simulations were performed with a blendof 67% iso-octane and 33% toluene measured by liquid volume, whichconverted to mass fractions is 62.2%/37.8% isooctane/toluene. This fuelblend is often used in laboratory testing as a reproduciblerepresentation of modern gasoline.

Analysis of the simulation results presented below in Table II showthat:

-   -   The average exhaust temperatures appear to be about 1152 K (879°        C.) with the use of vaporized gasoline, where maximum        temperatures are achieved at the exhaust valve opening. However,        the average exhaust temperatures at the valve and at the head        exit are about 1188 K (915° C.) and 1152 K (879° C.)        respectively.    -   Enthalpy available from exhaust gases (with a maximum exhaust        temperature of 1123K (850° C.)) for gasoline is about 1.559E+05        kJ/kmol.    -   For the gasoline simulation, the indicated engine efficiency        obtained was 40.1%.

TABLE II Predicted (simulated) engine performance, exhaust temperatures,fuel consumption and emissions for internal combustion engine (ICE)system (Lambda = 1, rpm = 3000) 100% Gasoline to ICE (67% iso-octane 33%toluene by liq vol - 62.2%/37.8% Fuel by mass, vaporized) LHV (MJ/kg)43.340 Indicated power (HP) 22.060 Indicated power (kW) 16.225 Indicatedmean effective pressure (bar) 11.630 Indicated specific fuel consumption(kg/kWh) 0.208 Indicated engine efficiency (%) 40.1 Average exhausttemperature @ valve (K) 1,185.0 Average exhaust temperature @ exit (K)1,151.9 Maximum exhaust temperature (K) 1,247.0 NOx (ppm) 3,575.0 NOx(g/kWh ind) 12.0 HC (ppm) 2,861.0 HC (g/kWh ind) 4.5 CO (ppm) 1,311.0 CO(g/kWh ind) 4.1 Total C in HC and CO (g Carbon/kWh ind) - 5.865 approx.Mass fraction of C in fuel entering engine 0.862 Total C in fuelentering engine 179.342 (g Carbon/kWh ind) CO₂ in exhaust (g CO₂/kWhind) - if all C into 657.586 CO₂ CO₂ in exhaust (ppm CO₂) - if all Cinto CO₂ 133,937.0 CO₂ in exhaust (vol % CO₂) - if all C into CO₂13.39370

Table II above shows that the average exhaust temperatures at theexhaust head exit is estimated to be around 1152 K (879° C.), and it hasbeen shown that exhaust gases emitted from a vehicle have a temperatureof around 520 to 580° C. Accordingly, the heat loss by the exhaust gaseswhile traveling through the exhaust system is about 300 to 360° C.

Table III below shows heat liberated (in kJ/kg) from a typical gasolinefuel as a result of combustion under the effect of varying air flows.Table IV below presents the composition of gas shown in mole fractionwhen a fuel is burned under excess air conditions.

TABLE III Heat liberated from fuel blend, kJ/kg for different values ofcombustion air. Excess air 100% C₈H₁₈ factor (λ) 39583.33 0.9 47947.06 147837.57 1.5

TABLE IV Products mole fractions for lean fuel burning (Excess Air)Percentage H₂ in Fuel XCO₂ XH₂O XN₂ XO₂ 0 0.08533334 0.096 0.7520.06666667Energy Availability from Exhaust Gases

As an example of energy recovery from waste heat of a vehicle engine,the following are results of testing performed by Clean PowerTechnologies:

-   -   With a diesel engine running at 1400 rpm and producing 405 bhp,        the exhaust gas temperature is 549° C.    -   At a mass flow rate of 0.46 Kg/s, the exhaust gas has an energy        value of 268 kJ/s    -   A heat exchanger can recover 250° C. from the exhaust gas, which        is 45% of the energy (i.e., approximately 121 kJ/s).    -   The system can then convert the recovered thermal energy to        mechanical power with a 19 KW output, providing an energy        efficiency of around 16% for the heat recovery.    -   The recovered energy is equivalent to recovering about 5-10% of        the vehicle engine running power.

Catalytic Converter Energy Recovery

Through research it is shown that there is also energy available fromthe catalytic converter of a vehicle. Specifically, the chemicalreactions occurring in a catalytic converter release a total heat of−2.8266×10⁶ kJ/kmol.

Both (1) the heat energy recovered from the waste energy generated bythe initial combustion of the fuel (i.e., approximately 121 kJ/s) and(2) the heat energy recovered from the catalytic converter (i.e.,−2.8266×10⁶ kJ/kmol) can be used to heat the reactants provided to thecatalytic reactor thereby facilitating the conversion of H₂O and CO₂ tohydrocarbon fuel as discussed above with respect to FIGS. 1-5.

The singular forms “a”, “an” and “the” include plural referents, unlessthe context clearly dictates otherwise. Optional or optionally meansthat the subsequently described event or circumstances may or may notoccur. The description includes instances where the event orcircumstance occurs and instances where it does not occur. Ranges may beexpressed herein as from about one particular value, and/or to aboutanother particular value. When such a range is expressed, it is to beunderstood that another embodiment is from the one particular valueand/or to the other particular value, along with all combinations withinsaid range.

While the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart in light of the foregoing description. Accordingly, it is intendedto embrace all such alternatives, modifications, and variations as fallwithin the spirit and broad scope of the appended claims. The presentinvention may suitably comprise, consist or consist essentially of theelements disclosed and may be practiced in the absence of an element notdisclosed.

Throughout this application, where patents or publications arereferenced, the disclosures of these references in their entireties areintended to be incorporated by reference into this application, in orderto more fully describe the state of the art to which the inventionpertains, except when these reference contradict the statements madeherein.

We claim:
 1. An on-board, catalytic apparatus comprising: a heatexchanger operable to extract thermal energy from exhaust gases of acombustion engine, the combustion engine powering propulsion of avehicle; a membrane separator operable to separate water and carbondioxide from the exhaust gases; and a catalytic reactor contained in abody of the heat exchanger, the catalytic reactor operable to: receivethe water and the carbon dioxide from the membrane separator; contain areaction of the water and the carbon dioxide that produces hydrocarbonfuel, the reaction being facilitated by a nano catalyst; and use thethermal energy from the heat exchanger to stimulate the reaction of thewater and the carbon dioxide.
 2. The apparatus as claimed in claim 1,wherein the nano catalyst is a multimetallic nano catalyst thatcomprises at least one metal from a group consisting of ruthenium,manganese, and nickel.
 3. The apparatus as claimed in claim 1, whereinthe nano catalyst is about 2 to 3 percent ruthenium, about 20 to 30percent nickel, and about 15 to 20 percent manganese.
 4. The apparatusesclaimed in claim 3, wherein the nano catalyst is about 2 percentruthenium, about 20 percent nickel, and about 15 percent manganese. 5.The apparatus as claimed in claim 1, wherein the membrane separatorcomprises: a selective membrane layer of a group consisting of asilica-based membrane layer, a carbon-based membrane layer, and azeolite membrane layer; and a support layer of a group consisting of aceramic support, a metallic support, and an alumina support.
 6. Theapparatus as claimed in claim 1, wherein the catalytic reactor isencompassed by the heat exchanger such that the thermal energy isdirected to a portion of the catalytic reactor holding the nanocatalyst.
 7. The apparatus as claimed in claim 6, wherein the catalyticreactor comprises multiple tubes for holding the nano catalyst, themultiple tubes providing increased surface area for receiving thethermal energy from the heat exchanger.
 8. The apparatus as claimed inclaim 1, wherein the hydrocarbon fuel comprises ethanol and propyne. 9.A process for on-board carbon dioxide conversion to hydrocarbon fuel,the process comprising: extracting thermal energy from exhaust gases ofa combustion engine, the combustion engine powering propulsion of avehicle; separating water and carbon dioxide from the exhaust gases;converting the water and the carbon dioxide to hydrocarbon fuel byperforming a reaction that is facilitated by a nano catalyst, thereaction being stimulated by the thermal energy extracted from theexhaust gases; and feeding the hydrocarbon fuel into the combustionengine for combustion.
 10. The process as claimed in claim 9, whereinthe nano catalyst is a multimetallic nano catalyst that comprises atleast one metal from a group consisting of ruthenium, manganese, andnickel.
 11. The process as claimed in claim 9, wherein the nano catalystis about 2 to 3 percent ruthenium, about 20 to 30 percent nickel, andabout 15 to 20 percent manganese.
 12. The process as claimed in claim11, wherein the nano catalyst is about 2 percent ruthenium, about 20percent nickel, and about 15 percent manganese.
 13. The process asclaimed in claim 9, further comprising cooling the exhaust gases toabout 200 to about 300 degrees centigrade prior to separating the waterand the carbon dioxide from the exhaust gases.
 14. The process asclaimed in claim 9, further comprising oxidizing carbon monoxide in theexhaust gases to produce carbon dioxide.
 15. The process as claimed inclaim 9, wherein the hydrocarbon fuel comprises ethanol and propyne. 16.The process as claimed in claim 15, wherein the reaction is5CO₂+5H₂O→C₂H₅OH+H₃C—C≡CH+7 O₂, wherein CO₂ is the carbon dioxide, H₂Ois the water, C₂H₅OH is the ethanol, H₃C—C≡CH is the propyne, and O₂ isoxygen.